Editors Selection (IGR: 7-1) | International Glaucoma Review #34

Editors Selection IGR 7-1

Clinical examination methods: Bloodflow and progression

Comment by Alon Harris on:

12994 Predictive value of colour Doppler imaging in a prospective study of visual field progression in primary open-angle glaucoma, Martinez A; Sanchez M, Acta Ophthalmologica Scandinavica, 2005; 83: 716-722

While the etiology of primary open angle glaucoma (POAG) was once believed to be only intraocular pressure-related, mounting evidence suggests that decreased ocular perfusion is partly responsible for the retinal ganglion cell apoptosis seen in POAG. Martinez and Sanchez (929) have investigated the retrobulbar hemodynamics of 49 patients with POAG over 36 months, utilizing color Doppler imaging. The authors have produced interesting findings regarding the ability of Pourcelot's resistive index (RI) in the ophthalmic artery and posterior ciliary arteries to predict which patients are likely to have glaucomatous progression and subsequent visual field loss. They provide RI discrimination points of 0.72 and 0.65 respectively, with the ophthalmic artery having a positive post-test probability of 90.5%.

An increased resistive index was predictive of progression

Although the authors measured IOP and systemic blood pressure, neither was found to be associated with an increased risk of disease progression. These findings are supported by the Baltimore Eye Survey, Egna-Neumarkt and Barbados Incidence Study of Eye Diseases, which found IOP to be a poor predictive risk factor in POAG. It would be beneficial if the authors could provide information regarding the ocular perfusion pressures of their subjects, as these large epidemiological studies found perfusion pressure to be a highly predictive independent risk factor for POAG.^1-3Additionally, it would be useful to compare other clinical methods of evaluating ocular blood flow, which investigate other ocular tissues, such as Heidelberg Retinal Flowmetry (HRF), scanning laser ophthalmoscopy, and retinal oximetry.⁴ The contribution of these retrobulbar RI cut-off points provide further evidence that vascular dysfunctions are present in POAG.

References

Tielsch JM, Katz J, Sommer A, Quigley HA, Javitt JC. Hypertension, perfusion pressure and primary open angle glaucoma. A population based assessment. Arch Ophthalmol 1995; 113: 216-221.
Bonomi L, Marchini G, Marraffa M, Bernardi P, Morbio R, Varotto A. Vascular risk factors for primary open angle glaucoma. The Egna-Neumarkt Study. Ophthalmology 2000; 107: 1287-1293.
Leske MC, Wu SY, Nemesure B, Hennis A. Incident open-angle glaucoma and blood blood pressure. Arch Ophthalmol 2002; 120: 954-959.
Rechtman E, Harris A, Kumar R, Cantor LB, Ventrpragada S, Desai M, Friedman S, Kagemann L, Garzozi HJ. An update on retinal circulation assessment technologies. Curr Eye Res 2003; 27: 329-343.

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